Maveropepimut-S, pembrolizumab and low dose cyclophosphamide in metastatic ovarian cancer: phase 1/2 PESCO trial

This investigator-initiated, open-label phase 1/2 clinical trial evaluates maveropepimut-S, a survivin-targeting vaccine, combined with pembrolizumab and low-dose cyclophosphamide in patients with recurrent epithelial ovarian cancer (ClinicalTrials.gov identifier: NCT03029403). The primary endpoints are safety and clinical efficacy measured by overall response rate and disease control rate. Secondary endpoints include recommended phase 2 dose, progression-free survival, overall survival, and survivin-specific immune response. Forty-seven patients are enrolled and forty-four are evaluable. Most treatment-related adverse events are grade 1 or 2, most commonly injection site reactions. The recommended phase 2 dose is 0.25 milliliters. The overall response rate is 23% and the disease control rate is 67%, with greater activity in platinum-sensitive disease. Median progression-free survival is 6.3 months in platinum-sensitive disease and 1.2 months in platinum-resistant disease. Survivin-specific immune responses occur in 62.5% of tested patients and correlate with clinical benefit. The combination demonstrates tolerability and sustained clinical activity.